算法复习1(冒泡、快排、折半)

冒泡

 1  static void BubbleSort()
 2         {
 3             int[] array = new int[] { 7, 3, 5, 8, 2 };
 4 
 5             for (int i = 0; i < array.Length; i++)
 6             {
 7                 for (int j = 0; j < array.Length - i - 1; j++)
 8                 {
 9                     if (array[j] > array[j + 1])
10                     {
11                         int temp = array[j];
12                         array[j] = array[j + 1];
13                         array[j + 1] = temp;
14                     }
15                 }
16             }
17             Array.ForEach(array, p => Console.Write(p));
18         }

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快排

        static int QuickSort(int[] array, int low, int high)
        {
            if (low >= high) return -1;

            int keyIndex = low;
            int key = array[low];


            while (low < high)
            {
                while (low <= high)
                {
                    if (key > array[high])
                    {
                        Swap(array, keyIndex, high);
                        keyIndex = high;
                        break;
                    }
                    high--;
                }

                while (low < high)
                {
                    if (key < array[low])
                    {
                        Swap(array, low, keyIndex);
                        keyIndex = low;
                        break;
                    }
                    low++;
                }
            }

            return keyIndex;
        }

        static void QuickSortRecursion(int[] array, int i, int j)
        {
            int index = QuickSort(array, i, j);

            if (index == -1) return;

            QuickSortRecursion(array, i, index - 1);
            QuickSortRecursion(array, index + 1, j);
        }

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二分

 1 static int DichoFind(int[] array, int num)
 2         {
 3             int i = 0;
 4             int j = array.Length - 1;
 5 
 6             while (i <= j)
 7             {
 8                 int mid = (i + j) / 2;
 9 
10                 if (array[mid] > num)
11                 {
12                     j = mid - 1;
13                 }
14                 else if (array[mid] < num)
15                 {
16                     i = mid + 1;
17                 }
18                 else
19                 {
20                     return mid;
21                 }
22             }
23 
24             return -1;
25         }

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